Orbital arteriovenous malformation mimicking cavernous sinus dural arteriovenous malformation

Aims - Orbital arteriovenous malformations (OAVM) are rare, mostly described with high flow characteristics. Two cases are reported with an OAVM of distinct haemodynamic abnormality. The clinical, angiographic features, and the management considerations are discussed. Methods - Case review of two patients with dural AVM (DAVM) who presented to referral neuro-ophthalmology and endovascular services because of clinical symptoms and signs consistent with a cavernous sinus dural AVM. Results - In each patient, superselective angiography revealed a small slow flow intraorbital shunt supplied by the ophthalmic artery. The transarterial and transvenous endovascular approaches to treat the malformation were partially successful. Although, the abnormal flow was reduced, complete closure of the DAVM could not be accomplished without significant risk of iatrogenic injury. Neither patient's vision improved after intervention. Conclusion - A DAVM in the orbit can cause similar clinical symptoms and signs to those associated with a cavernous sinus DAVM. Even with high resolution magnetic resonance imaging, only superselective angiography can identify this small intraorbital slow flow shunt. The location in the orbital apex and the small size precludes a surgical option for treatment. The transarterial and transvenous embolisation options are limited.